BLADE COOLING AND SEALING SYSTEM
A cooled component for a gas turbine engine, for example a turbine rotor blade, is provided. The component has an internal cooling flow passage. Cooling air is passed through the internal cooling flow passage to remove heat from the component and thereby reduce its temperature. The cooling air is bled from the internal cooling passage after it has passed through a portion of the passage into an internal bleed flow passage. This bled air is then used in a seal. Thus, some of the cooling air that enters the internal cooling flow passage is used both to cool the component and to form a seal, for example with another component.
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This application is based upon and claims the benefit of priority from British Patent Application Number 1112880.8 filed 27 Jul. 2011, the entire contents of which are incorporated by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention concerns cooling and sealing arrangements in a gas turbine engine. In particular, the present invention concerns a method and apparatus for using flow to cool components in a gas turbine engine and seal between components of a gas turbine engine.
2. Description of the Related Art
The performance of a gas turbine engine, for example measured in terms of efficiency or specific output, may be improved by increasing the turbine gas temperature. It is therefore generally desirable to operate the turbine at the highest possible temperature. For a given gas turbine configuration (for example in terms of engine cycle compression ratio or bypass ratio), increasing the turbine entry gas temperature will produce more specific thrust (eg engine thrust per unit of air mass flow). However as turbine entry temperatures increases, the life of an uncooled turbine falls, necessitating the development of better materials and the introduction of internal air cooling.
Therefore, in order to cool turbine rotor blades and/or stator vanes (or at least to cool the aerofoil portions thereof), internal cooling passages are generally formed within the aerofoils. These internal cooling passages allow cooling air to be passed through the blades (or vanes) to remove heat through convection. The cooling air is typically taken from flow through a cooler part of the engine. For example, cooling air may be bled from the compressor, prior to combustion, for example from the HP compressor. Typical cooling air temperatures (for example at maximum take off condition) are between 700 and 900 K. Gas temperatures in the turbine can be in excess of 2100 K. Typically, cooling flow may enter the aerofoil via a fixture portion of the blade (at the radially inner end of the blade), pass through the blade in a substantially radial direction towards the the tip, and then exit through the tip (at the radially outer end of the blade). Such cooling flow 100 is shown in the
Generally, passing more cooling air through the blade allows the size (for example the mass) of the blade to be reduced. This has advantages in terms of engine mass and, in the case of a rotating blade, reduced centripetal loads. However, these advantages are at the expensive of increasing the bleed flow, for example from the compressor prior to combustion. Any air that is bled from the compressor prior to combustion cannot be used to burn fuel in the combustor, and therefore cannot be used to generate useful work in the turbine. As such, increasing cooling flow to the blades generally allows their weight to be reduced and/or their life to be increased, at the expense of a reduction in engine performance.
In addition to cooling flow requirements, air is required for use in sealing various components in a gas turbine engine. For example, sealing flow is required to seal between rotor and stator rims. Once again, the sealing air is provided from elsewhere in the engine. Typically, the sealing air may also be bled from the compressor. Such sealing flow 122, 124 is also shown in the
As mentioned above, air that is bled from the compressor prior to combustion (i.e. air that has bypassed the combustor) cannot be used to generate useful work. Extracting air from the compressor, for example for cooling the hot turbine components or for providing a sealing flow, therefore has an adverse effect on engine performance, such as operating efficiency. Therefore, it is desirable to reduce the amount of air that is bled from the compressor. However, it is also desirable to retain or improve cooling to the turbine blades and/or vanes, for example to reduce their mass.
According to an aspect, there is provided a blade or vane for a gas turbine engine. The blade or vane comprises a cooling fluid inlet configured to allow cooling fluid into the blade or vane. The blade or vane comprises a cooling fluid outlet configured to allow cooling fluid out of the blade or vane. The blade or vane comprises an aerofoil that, in use, is gas-washed by a working fluid of the gas turbine engine. The blade or vane comprises a platform from which the aerofoil extends (in a direction that may be said to be radially outward). The blade or vane comprises an internal cooling flow passage between the cooling fluid inlet and the cooling fluid outlet configured to channel cooling fluid through the interior of the blade or vane (for example at least through the aerofoil portion of the blade or vane). The blade or vane comprises an internal bleed flow passage in fluid communication with the internal cooling flow passage at a bleeding position, and configured to bleed a portion of the cooling fluid from the internal cooling flow passage for use as a sealing flow. The blade or vane comprises a sealing flow outlet through which fluid from the internal bleed flow passage exits the blade or vane, the sealing flow outlet being positioned to allow the sealing flow to be used in a seal during operation. The internal cooling flow passage extends through at least a part of the aerofoil before the sealing flow is bled off at the bleeding position (for example during operation of the gas turbine engine). The cooling fluid inlet (71) is located radially inward of the platform (64) (for example in a location that is radially inward of the platform when the blade or vane is in use, i.e. when installed in the gas turbine engine). The sealing flow outlet (82) is located radially inward of the platform (64) (for example in a location that is radially inward of the platform when the blade or vane is in use, i.e. when installed in the gas turbine engine).
The aerofoil may include aerodynamic surfaces that, in operation, are gas-washed by the working fluid, such as a suction surface, a pressure surface, and a platform from which the suction surface and pressure surface extend. The blade or vane may comprise sealing features which may combine or interact with (for example interlock with, abut, or nearly abut) neighbouring surfaces (for example of neighbouring blades or vanes) of a gas turbine engine to form a seal when assembled. The blade or vane may optionally include a shroud at its tip. The shroud may include sealing features to prevent or reduce over-tip leakage flow, for example in blade embodiments. The shroud may extend around the entire outer circumference of the blades. Alternatively, the blade or vane may have a partial shroud, or winglet, at its tip (for example extending around a portion of the segment between the blades). Alternatively still, the blade or vane may have no shroud at its tip.
Such an arrangement of blade or vane (which may be a rotor blade or a stator vane, for example of a turbine) means that at least some of the flow that is used for cooling the blade or vane is also used as sealing flow in a seal. The seal may be any suitable seal in the gas turbine engine, for example between axially spaced components, such as a rotor blade or stage and a downstream or upstream stator blade or stage. For example, part of the cooling flow that enters the blade or vane may pass through part of the internal cooling flow passage to cool the blade, and then be bled from the internal cooling passage for use in a seal. For example, the cooling flow may pass into a least a part of the inside of the aerofoil portion of the blade or vane before being bled off at the bleeding position. This may mean that at least a part of the gas washed surface which may be exposed to the higher temperatures in the turbine may be cooled before the flow is bled off to be used as sealing flow. Even if the cooling flow passes through a part of the internal cooling passage within the aerofoil before being bled off, the bleeding position may still be within a different part of the blade or vane (i.e. the bleeding position need not be within the aerofoil portion of the blade or vane, although in some embodiments it may be).
The total amount (i.e. mass flow rate) of flow (for example air) that is bled, for example from the compressor, to achieve a given level of blade cooling may thus be reduced (for example minimized), for example compared with conventional arrangements. Additionally or alternatively, the level of blade cooling may be increased for a given amount of air that is bled from the compressor.
The internal cooling flow passage may be a multipass cooling flow passage. Each pass may be arranged to carry cooling fluid in either a substantially radially outward direction or a substantially radially inward direction. The bleeding position may be after at least one pass through the internal cooling passage from the cooling fluid inlet. For example, the bleeding position may be after two passes through the internal cooling passage, e.g. one pass in the radially outward direction and one pass in the radially inward direction.
The radially outward and radially inward directions may be aligned with a longitudinal direction, or chordwise direction, of the blade or vane (or the aerofoil portion thereof). The radially outward direction may correspond to a root-to-tip direction of the aerofoil. The radially outward and radially inward directions may refer to the directions relative to a gas turbine engine (for example an axial flow gas turbine engine), for example when the aerofoil is installed in the gas turbine engine.
Arranging the aerofoil in this manner ensures that the sealing flow that exits through the sealing flow outlet has already passed through a part of the internal cooling flow passage that extends along the chord of the aerofoil, and thus removed heat from along the chord of the aerofoil, at least, before it is used as a sealing flow. This may be advantageous in removing heat evenly from the aerofoil, for example to avoid localised hot-spots being observed during operation.
The internal cooling flow passage may comprise an s-shape. Such a shape may be referred to as a serpentine shape.
The internal cooling flow passage may thus be a continuous passage. For example, the passes through the blade or vane may be joined by a bend (which may turn through substantially 180 degrees, and may or may not be in the aerofoil portion of the blade or vane) towards either the radially outward or radially inward direction. Such an arrangement may form the s-shape.
Arranging the internal cooling flow passage to be an s-shape may enable the cooling air to be directed inside the blade or vane as required. It may also provide convenient bleeding position to bleed the sealing flow from the internal cooling flow passage, for example at the bends in the passage.
The blade or vane may comprise a fixture for attaching the blade or vane to a gas turbine engine. The fixture may comprise an attachment portion, which may be a fir tree for attaching a blade to a disc, for example. The fixture may comprise a shank. The shank may be between the fir tree and the aerofoil. The fixture may comprise the platform. The aerofoil may extend from the platform. The surface of the platform from which the aerofoil extends may be exposed to the working fluid of the gas turbine engine during operation.
The cooling fluid inlet may be located in the fixture, for example in the shank of a rotor blade. The cooling fluid inlet is radially inward of the platform. This may be convenient, for example, if the cooling flow is provided from towards the axial centreline of the engine. Additionally or alternatively, it may be convenient if the blade or vane is a rotor blade.
The sealing flow outlet may be located in the fixture, for example in the shank of a rotor blade. The sealing flow outlet is radially inward of the platform. This may be convenient if, for example, the sealing flow is to be used in a seal towards the radially inner side of the vane or blade, for example a rim seal.
The cooling flow outlet may be located towards the radially outer end of the blade or vane. For example, the cooling flow outlet may be located towards the tip of the aerofoil. This may be convenient if, for example, the cooling fluid may be used for other purposes at the radially outer end of the aerofoil. For example, cooling fluid (such as air) exiting from the radially outer end of the aerofoil may be used to cool the tip of the aerofoil, for example the tip of a rotor blade. By way of further example, cooling fluid exiting the radially outer end may be used to cool the casing shroud within which the rotor blades rotate.
The sealing flow may be removed (bled) from the internal cooling flow passage as close to the sealing flow outlet as possible. For example, if the sealing flow is used in a seal towards the radially inner end of the blade or vane, the bleeding position may be located in the radially inner end of the blade or vane, for example in the fixture. This may allow the maximum possible cooling potential to be extracted from the cooling flow. It may also simplify the arrangement of the internal cooling flow passage and internal bleed flow passage.
The bleeding position and the internal bleed flow passage may both be provided within the fixture. This may allow all of the features relating to the sealing flow to be located in close proximity, thereby allowing maximum cooling and/or a simple arrangement of features.
In use, the blade or vane may have an upstream side and a downstream side defined relative to a flow direction through the gas turbine engine. The upstream side may correspond to the leading edge of the blade or vane and the downstream side may correspond to the trailing edge of the blade. The sealing flow outlet may be located on the downstream side of the blade or vane. Alternatively, the sealing flow outlet may be provided on the upstream side of the blade or vane.
The blade or vane may comprise two sealing flow outlets. One of the sealing flow outlets may be located at the downstream side of the aerofoil, and the other may be located at the upstream side of the aerofoil. This may enable sealing flow to be provided to one or both of an upstream seal and a downstream seal. One or both of the seals may form at least a part of a circumferential seal.
The bleeding position may be at least 20% along the length of the internal cooling flow passage from the cooling fluid inlet. In an embodiment, the bleeding position is in the range of from 30% to 90% along the length of the internal cooling flow passage. In an embodiment, the bleeding position is in the range of from 40% to 80% along the length of the internal cooling flow passage. In an embodiment, the bleeding position is in the range of from 50% to 70% along the length of the internal cooling flow passage. In an embodiment, the bleeding position is on the order of 60% along the length of the internal cooling flow passage.
Providing the bleeding position at least 20% along the length of the internal cooling flow passage ensures that the flow that is to be used for sealing extracts a significant amount of heat from the blade or vane before it is bled from the internal cooling flow passage. The cooling air will tend to heat up as it moves through the internal cooling flow passage. Therefore, bleeding the cooling flow only after at least 20% of the distance from the inlet ensures that the cooling air is not bled off when it is at its coolest, and thus its most effective, towards the start of the internal cooling flow passage.
In the range of from 10% to 70% of the mass flow rate of cooling flow entering the blade through the cooling flow inlet may be bled through the internal bleed flow passage and out through the sealing flow outlet. In some embodiments, this may be in the range of from 15% to 60%, or 20% to 50%, or 25% to 40%, or on the order of 30%. As such, a significant proportion of the flow passing into the blade or vane through the cooling flow inlet may be bled off to provide sealing flow. In some embodiments, more than 70% (for example substantially all) of the flow passing into the blade or vane through the cooling flow inlet may be bled off to provide sealing flow.
The internal bleed flow passage may have a dog-leg shape. The dog leg shape may be arranged such that the internal bleed flow passage passes to the side of the internal cooling flow passage when viewed in the radial direction. Such a portion of the bleed flow passage may be referred to as a gallery. Arranging the internal bleed flow passage to have a dog-leg may allow the sealing flow outlet to be positioned in the desired place, by allowing the internal bleed flow passage to pass to the side of the internal cooling flow passage.
The blade or vane may comprise effusion cooling flow outlets configured to use cooling flow, for example from the internal cooling flow passage, to supply surface cooling to the aerofoil. This may be an efficient way to cool the blade or vane, for example by forming a cooler air film over the surface of the blade or vane to minimize its interaction with the hot working gas. The cooling flow outlet itself may be an effusion cooling flow outlet.
According to an aspect, there is provided a compressor or turbine for a gas turbine engine having at least one rotor stage and at least one stator stage, and at least one of the rotor blades or stator blades is a blade or vane as described herein. According to one aspect, all blades in one or more rotor and/or stator stages of a compressor and/or turbine may be as described herein. The invention may be particularly advantageous in turbines, where the gas temperatures are higher than those in compressors. However, the invention described herein may apply to compressors as well as turbines.
According to an aspect, there is provided rotor-stator stage for a gas turbine, wherein: the rotor stage comprises at least one blade according to any one of the preceding claims and/or the stator stage comprises at least one vane according to any one of the preceding claims; and the sealing flow exiting from the sealing flow outlet is used as a seal between the rotor stage and the stator stage.
For example, the rotor stage may have blades as described herein that provide a sealing flow for a seal between the rotor stage and a neighbouring stator stage, for example the neighbouring downstream stator stage. The sealing flow may thus provide a gas (for example air) seal between a rotatable rotor stage and a stationary stator stage. The sealing flow may provide a rim seal.
According to an aspect, there is provided a method of using a flow in a gas turbine engine to cool a blade or a vane in a stage of the gas turbine engine and to seal between a rotor stage and a stator stage of the gas turbine engine. The blade or vane comprises an aerofoil that, in use, is gas-washed by a working fluid of the gas turbine engine. The method comprises using at least a part of the flow both to cool the aerofoil and to seal between the stages.
Such a method may provide any one or more of the advantages described herein.
The method may comprise cooling the aerofoil by passing a cooling flow into the blade or vane, through an internal cooling passage inside the aerofoil, and out of the blade or vane through a cooling fluid outlet. The method may comprise bleeding at least a part of the cooling flow passing through the internal cooling passage through a sealing flow outlet in the blade or vane before it reaches the cooling fluid outlet. The method may comprise using the flow passing out of the blade through the sealing flow outlet in a seal between the stages.
The flow that is used for cooling and sealing may be bled from a compressor of the gas turbine engine before entry into a combustor. Thus, using at least a portion of the flow for both cooling and sealing means that less air needs to be bled from the compressor and/or that more heat can be removed from a given blade or vane for a given amount of air bled from the compressor.
Embodiments of the invention will now be described by way of example only, with reference to the accompanying diagrammatic drawings, in which:
With reference to
The gas turbine engine 10 works in a conventional manner so that air entering the intake 11 is accelerated by the fan 12 to produce two air flows: a first air flow A into the intermediate pressure compressor 13 and a second air flow B which passes through the bypass duct 22 to provide propulsive thrust. The intermediate pressure compressor 13 compresses the air flow A directed into it before delivering that air to the high pressure compressor 14 where further compression takes place.
The compressed air exhausted from the high-pressure compressor 14 is directed into the combustion equipment 15 where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through, and thereby drive, the high, intermediate and low-pressure turbines 16, 17, 18 before being exhausted through the nozzle 19 to provide additional propulsive thrust. The high, intermediate and low-pressure turbines 16, 17, 18 respectively drive the high and intermediate pressure compressors 14, 13 and the fan 12 by suitable interconnecting shafts.
As the air passes through the gas turbine engine 10 it is heated to high temperatures. In particular, the first airflow B reaches high temperatures as it passes, through the core of the engine. Typically, particularly high temperatures may be reached at the exit of the combustion equipment 15, and as the air subsequently passes through the high, intermediate and low-pressure turbines 16, 17, 18.
Gas temperatures in the turbine can be in excess of 2100 K. This may be higher than the melting point of the materials from which the turbine components are manufactured. Furthermore, as mentioned herein, it is desirable to operate the turbine at the highest possible temperature because generally, for a given gas turbine configuration, increasing the turbine entry gas temperature will produce more specific thrust.
Therefore, in order to cool turbine rotor blades and/or stator vanes (for example to cool the aerofoil portions thereof), internal cooling passages may be formed within the blades. These internal cooling passages allow cooling air to be passed through the blades (or vanes) to remove heat through convection.
A conventional arrangement of a turbine rotor blade having cooling passages 100 formed therethrough is shown in
In the conventional arrangement shown in
Typically, cooling air may be bled from the compressor 13, 14, prior to combustion, for example from the HP compressor. Typical cooling air temperatures are between 700 and 900 K. This air that is bled from the compressor 13, 14 prior to combustion cannot be used to burn fuel in the combustor 15, and therefore cannot be used to generate useful work in the turbine 16, 17, 18. As such, providing cooling air 100 to the turbine blade 30 generally results in a reduction in engine efficiency.
In addition to the cooling air 100 that is provided to the turbine blade 44 from the compressor 13, 14 in the
In the
Thus, in the
A turbine blade 60 according to an embodiment of the invention is shown in
The turbine blade 60 has a fixture 62, a platform 64, an aerofoil (or aerofoil portion) 66, and a tip 68. An internal cooling flow passage 70 passes through the inside (interior) of the blade 60. Cooling fluid (for example cooling air) 200 passes through the internal cooling flow passage 70, thereby cooling the turbine blade 60.
The fixture 62 may allow the blade 60 to be attached to a corresponding component of a gas turbine engine, for example to a turbine disc (not shown). The term fixture 62 may be used to refer to parts of the blade 60 that are radially inward of the platform 64. The fixture 62 may not be gas washed by the working fluid passing through the turbine 16, 17, 18. In the
The tip 68 of the blade 60 is shaped to form a circumferential seal with the case 69. The blade 60 shown in
The internal cooling flow passage 70 has a cooling fluid inlet 71 to the blade 60. In the embodiment shown in
As mentioned above, the cooling fluid 201 entering the cooling fluid inlet 71 may be provided from any suitable source of relatively cool fluid, such as from the compressor 13, 14 prior to combustion. By way of example, in the range of from 0.2% to 10%, for example 0.5% to 5%, for example 0.75% to 2%, for example 1% to 1.5% of flow through the compressor may be bled off to enter the cooling fluid inlet(s) 71 for each stage that is cooled. The amount of compressor air that is bled may be dependent on the stage that is cooled, and the temperature/cooling requirements thereof. Purely by way of example only, an intermediate pressure turbine stage may require in the range of from 0.2% to 2% of compressor air to be bled to it, and a high pressure turbine stage may require in the range of from 1% to 10% of compressor air to be bled from it. Of course, other amounts of compressor air (i.e. outside of these ranges) may be required for a given stage.
In the
The internal cooling flow passage 70 forms a serpentine, or ‘s’ shape 76 at least partially within the aerofoil portion 66 in the
In alternative embodiments, the internal flow passage may take a different shape. Any suitable shape could be used. By example only, the internal cooling flow passage could have 1, 2, 3 (as in the case of the
In the
Although not shown in
The blade 60 comprises an internal bleed flow passage 80 in fluid communication with the internal cooling flow passage 70 at a bleeding position 81. At the bleeding position 81, the internal cooling flow passage 70 and the internal bleed flow passage 80 are fluidly interconnected. At the bleeding position 81, some of the air 205 flowing through the internal cooling flow passage 70 continues through the rest of the internal cooling flow passage 70, and some of the air 210 flowing through the internal cooling flow passage 70 before the bleeding position 81 enters and flows through the internal bleed flow passage 80.
The air 210 that is bled off the cooling passage 70 at the bleeding position 81 may be used in a seal. Thus, the bled air 210 may be referred to as sealing air 210. The sealing air 210 may be used, for example, to seal one or more gaps between the turbine blade 60 and neighbouring components, such as neighbouring stator vanes. By way of example, in the embodiment of
In
In
The proportion of the flow 210 that enters the internal bleed flow passage 80 may be determined by, for example, the relative size (for example cross-sectional area, or effective flow area) of the internal bleed flow passage 80 and the cooling flow passage 75 downstream of the bleeding position 81. Additionally or alternatively, the proportion of the flow 210 that enters the internal bleed flow passage 80 may be determined by the connection geometry between the internal cooling flow passage 70 and the internal bleed flow passage 80 at the bleeding position 81. For example, the angle between the internal cooling flow passage 70 and the internal bleed flow passage 80 may have an impact, as may the internal wall shape.
The proportion 210 of the flow 200 in the internal cooling flowing flow passage 74 upstream of the bleeding position 81 that enters the bleed flow passage 80 may be in the range of from 5% to 75%, for example on the order of 30%.
According to the arrangements described herein, at least a portion of the air that is used to cool a turbine component (such as a turbine blade 60) may also be used to provide a sealing flow 210. This means that, for a given mass flow rate of sealing flow (which may be determined by the geometry to be sealed), and a given level of component (for example turbine blade) cooling (which may be determined by, for example, the maximum component operating temperature for a given service life), the total mass flow that needs to be bled from the compressor 12, 13, 14 (for example) may be reduced. In turn this means that more air can pass through the combustor to burn fuel, and thus more useful work can be extracted by the turbine 17, 18.
Additionally or alternatively, the total amount of air that is bled from the compressor 12, 13, 14 may be kept substantially the same as arrangements where the cooling flow and sealing flow are separate (such as that shown in
In some embodiments, the advantages described herein may be combined, such that both less mass flow rate of air is bled from the compressor 12, 13, 14 and more cooling air is provided to the blade 60, and thus its mass may be lower.
In some embodiments, additional sealing flow 230 may be provided to augment the bled sealing flow 210. This is represented in the
The rear platform rim seal 98 that the bled sealing air 210 is used to seal in the
The bled sealing air 210 may exit through the sealing flow outlet 82 in any suitable position relative to the seal 98. For example, the sealing flow outlet 82 may be upstream of the seal 98 and/or within or into the seal 98. By way of example, in the
In the
The internal cooling flow passage 70 and the internal bleed flow passage 80 may be arranged so as not to interact with each other, for example at any position other then the bleed flow position. In the
Details of the internal passages 70, 80 in the shank 63 of the
At least some of the examples described herein refer to rotor blades, for example high pressure, low pressure or intermediate pressure turbine rotor blades. The invention may be embodied in other types of components, for example stator vanes, for example high pressure, low pressure or intermediate pressure turbine stator vanes. The invention may, by way of example only, be embodied in any component that has internal cooling passages (or components in which internal cooling flow passages may be desirable). For example, embodiments of the invention may include those components that do not currently include internal cooling flow passages, but in which internal cooling flow passages may be desirable if, for example, the bleed flow (for example from an upstream compressor) may be reduced by using the bleed flow both for cooling purposes and for sealing in or between components. Any feature described and/or claimed herein may combined with any other compatible feature described in relation to the same or another embodiment.
Claims
1. A blade or vane for a gas turbine engine comprising:
- a cooling fluid inlet configured to allow cooling fluid into the blade or vane;
- a cooling fluid outlet configured to allow cooling fluid out of the blade or vane;
- an aerofoil that, in use, is gas-washed by a working fluid of the gas turbine engine, the aerofoil extending from a platform;
- an internal cooling flow passage between the cooling fluid inlet and the cooling fluid outlet configured to channel cooling fluid through the interior of the blade or vane;
- an internal bleed flow passage in fluid communication with the internal cooling flow passage at a bleeding position, and configured to bleed at least a portion of the cooling fluid from the internal cooling flow passage for use as a sealing flow; and
- a sealing flow outlet through which fluid from the internal bleed flow passage exits the blade or vane, the sealing flow outlet being positioned to allow the sealing flow to be used in a seal during operation, wherein:
- the internal cooling flow passage extends through at least a part of the aerofoil before the sealing flow is bled off at the bleeding position;
- the cooling fluid inlet is located radially inward of the platform; and
- the sealing flow outlet is located radially inward of the platform.
2. A blade or vane according to claim 1, wherein:
- the internal cooling flow passage is a multipass cooling flow passage, each pass being arranged to carry cooling fluid in either a radially outward direction or a radially inward direction; and
- the bleeding position is after at least one pass through the internal cooling passage from the cooling fluid inlet.
3. A blade or vane according to claim 1, wherein the internal cooling flow passage comprises an s-shape.
4. A blade or vane according to claim 1, further comprising a fixture for attaching the blade or vane to a gas turbine engine, wherein:
- the cooling fluid inlet is located in the fixture; and
- the sealing flow outlet is located in the fixture.
5. A blade or vane according to claim 1, wherein the cooling flow outlet is located towards the radially outer end of the blade or vane.
6. A blade or vane according to claim 4, wherein the bleeding position is located in the fixture.
7. A blade or vane according to claim 1, wherein:
- the blade or vane, in use, has an upstream side and a downstream side defined relative to a flow direction through the gas turbine engine; and
- the sealing flow outlet is located on the downstream side of the blade or vane.
8. A blade or vane according to claim 1, wherein the bleeding position is at least 20% along the length of the internal cooling flow passage from the cooling fluid inlet.
9. A blade or vane according to claim 1, wherein in the range of from 10% to 70% of the mass flow rate of cooling flow entering the blade through the cooling flow inlet is bled through the internal bleed flow passage and out through the sealing flow outlet.
10. A blade or vane according to claim 1, wherein the internal bleed flow passage has a dog-leg shape such that it passes to the side of the internal cooling flow passage when viewed in the radial direction.
11. A compressor or turbine for a gas turbine engine having at least one rotor stage having rotor blades and at least one stator stage having stator vanes, wherein at least one of the rotor blades or stator vanes is a blade or vane according to claim 1.
12. A rotor-stator stage for a gas turbine, wherein: the rotor stage comprises at least one blade or vane according to claim 1; and
- the sealing flow exiting from the sealing flow outlet is used in a seal between the rotor stage and the stator stage.
13. A method of using a flow in a gas turbine engine to cool a blade or a vane in a stage of the gas turbine engine and to seal between a rotor stage and a stator stage of the gas turbine engine, wherein:
- the blade or vane comprises an aerofoil that, in use, is gas-washed by a working fluid of the gas turbine engine; and
- the method comprising using at least a part of the flow both to cool the aerofoil and to seal between the stages.
14. A method according to claim 13, comprising:
- cooling the aerofoil by passing a cooling flow into the blade or vane, through an internal cooling passage inside the aerofoil, and out of the blade or vane through a cooling fluid outlet;
- bleeding at least a part of the cooling flow passing through the internal cooling passage through a sealing flow outlet in the blade or vane before it reaches the cooling fluid outlet; and
- using the flow passing out of the blade through the sealing flow outlet in a seal between the stages.
15. A method according to claim 13, wherein the flow that is used for cooling and sealing is bled from a compressor of the gas turbine engine before entry into a combustor.
16. A rotor-stator stage for a gas turbine, wherein: the rotor stage comprises at least one blade and vane according to claim 1; and
- the sealing flow exiting from the sealing flow outlet is used in a seal between the rotor stage and the stator stage.
Type: Application
Filed: Jul 11, 2012
Publication Date: Jan 31, 2013
Applicant: ROLLS-ROYCE PLC (London)
Inventors: ALEXANDER J. BURT (BRISTOL), KEITH C. SADLER (BRISTOL), KEVIN GORTON (BRISTOL)
Application Number: 13/546,678
International Classification: F01D 5/08 (20060101);